1. Field of the Invention
The present invention relates to a novel quinoline derivative and a salt thereof possessing a superior anti-acetylcholinesterase activity, an intermediate for the preparation of the quinoline derivative and a salt thereof, and a pharmaceutical composition comprising these compounds.
2. Description of the Background
Senile dementia is broadly classified into the cerebral vascular disorder type and the Alzheimer type. Even though causes of Alzheimer type senile dementia have still to be elucidated, a number of attempts have been undertaken to treat or cure the disease by the administration of cholinergic drugs, since the theory of the cholinergic effects was proposed. For example, there is a report on the study of curing senile dementia by the use of physostigmine which is a typical acetylcholinesterase inhibitor [Neurology, 8, 397 (1978)]. Japanese Patent Laid-open (Kokai) Nos. 148154/1986, 141980/1988, 166881/1988, 73/1989, 250353/1989, 167267/1990, J. Medicinal Chemistry, 31, 1278 (1988), and J. Medicinal Chemistry, 32, 1805 (1989) report about anti-acetylcholinesterase effects of aminoacridine derivatives, claiming the effectiveness of the compounds in the curing of senile dementia. Summers et al. report the effectiveness of 9-amino-1,2,3,4-tetrahydro-acridine (Tacrine) and lecithin in the improvement in symptoms of senile dementia patients of Alzheimer type [The New England Journal of Medicine, 315, 1241 (1986)].
These known acetylcholinesterase inhibitors, however, do not exhibit sufficient curative effects and are accompanied by side effects such as liver disorders and the like.
The development of a compound useful as a medicine for curing dementia, which possesses an excellent anti-acetylcholinesterase effect with a least side effects, has therefore been desired.
In view of this situation, the present inventors synthesized various compounds and studied their pharmaceutical effects, and found that novel quinoline derivatives represented by the following formula (I) or their salts and novel piperidine derivatives represented by the following formula (II) or their salts exhibited excellent anti-acetylcholinesterase effects and were effective for curing dementia such as amnesic syndrome. Such a finding has led to the completion of this invention.